Effluent sampling method and apparatus for a gas chromatographic procedure



Nov. 17, 1970 P. GORNE HAL EFFLUENT SAMPLING METHOD AND APPARATUS FOR A GAS CHROMATOGRAPHIC PROCEDURE Filed Sept. 30, 1968 INVENTORS. PHMA/P 606W? $77SV6N H EBA/M66 @A A TTOEA/EVS United States Patent 3,540,852 EFFLUENT SAMPLING METHOD AND APPARATUS FOR A GAS CHROMATO- GRAPHIC PROCEDURE Phillip Gorne, Escondido, and Steven H. Kramer, San

Diego, Calif., assignors to Gordon S. Lacy, doing business as Pacific Research Laboratory, Escondido, Calif.

Filed Sept. 30, 1968, Ser. No. 763,814 Int. Cl. B011 5/02; G011: 1/00 U.S. Cl. 23-259 8 Claims ABSTRACT OF THE DISCLOSURE In a chromatographic procedure, an eflluent sampling method and apparatus for collecting a minute quantity of a gaseous constituent by passing the effluent sample through a syringe whose plunger is absent into a solvent for the effluent, the solvent flooding the tip of the syringe needle. After the sample has been absorbed the syringe plunger is replaced and manipulated to withdraw the solution into captivity within the syringe preliminary to further processing.

This invention relates to chromatography apparatus and more particularly to an improved apparatus and method for collecting a minute gaseous constituent preliminary to analysis, measurement and further processing of the gas.

An excellent technique frequently availed of in analyzing a mixture of substances utilizes gas chromatography because of the excellent high-efficiency distillation capabilities of a gas chromotograph. This equipment has the capability of separating a solution or mixture into its component parts quickly, simply, and with greater reliability than is attainable in many instances using classical wet chemical techniques. The usefulness of such techniques can be refined still further if the separated components can be captured and subjected to further analytical tests as typically, infrad-red, ultra-violet, nuclear magnetic resonance or mass spectroscopy.

However, the usefulness of these techniques has been limited in certain cases owing to difliculties experienced in capturing certain effluents produced from low boiling fluids. In these casesattemps have been made to employ super-cooling to condense the vapor but this requires a quartz tube and a coolant such as liquid nitrogen or Dry Ice. The necessary equipment is expensive and the required coolants may not be readily available at the proper time or place. Another expedient sometimes resorted to is the use of special adapters or sample cells designed to capture the component in vapor form. This technique is subject to the severe handicap of high cost and is not economically feasible in many cases.

The serious shortcomings and disadvantages of the foregoing previously proposed techniques are obviated by the present invention employing simple adaptations and equipment customarily present in the laboratory and requiring a minimum of training and expertise for its successful execution. By way of example, the present invention makes use of a precision syringe of the type having a readily removable plunger. After removing this plunger the inlet end of the syringe is connected in a gastight manner by flexible hose to the outlet for a particular eflluent from standard chromotographed equipment. The needle end of the syringe is associated with means for maintaining it submerged in a miniature container for a liquid solvent for the efliuent to be captured and analyzed. Suitable means for holding this container in place desirably include a larger container held releasably secured to the syringe barrel by means of a resilient stopper. An

inert gas is usually employed as a carrier to facilitate conducting the gaseous constituent to be analyzed into the solvent, the carrier gas being non-soluble in the solvent and being purged to the atmosphere through a suitable vent opening. After the sample has been absorbed the supply tube is disconnected and the syringe plunger is reassembled and employed to withdraw the solution and the absorbed eflluent into the syringe barrel following which this sample is subjected to analysis and measurement by known techniques.

It is therefore a primary object of this invention to provide an improved chromatographed apparatus for collecting minute quantities of a gaseous efl luent and for holding the substance captive for analysis.

Another object of the invention is the provision of simple, inexpensive, easily operated apparatus for collecting a small quantity of a gaseous efiluent at room temperature without need for a super coolant.

Another object of the invention is the provision of an inexpensive, easily practiced method and technique for collecting a sample of a fluid constituent from chromatographed equipment or the like and retaining it captive while subjecting it to analysis.

Thees and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated.

FIG. 1 is a vertical sectional view through a preferred embodiment of the invention apparatus arranged for collecting a gas constituent; and

FIG. 2 is a cross-sectional view similar to FIG. 1 but showing the invention apparatus disconnected from the chromatograph and with the syringe plunger installed for use in withdrawing the sample into the syringe.

Referring to FIGS. 1 and 2, there is shown one preferred embodiment of the invention apparatus designated generally 10. This apparatus includes a precision laboratory syringe having a barrel 11 fitted with a fluidtight plunger 12 reciprocal within the barrel. Detachably secured to the lower end of the barrel by a conventional fitting 13 is a hollow needle 14.

To facilitate the use of this syringe in accordance with principles of this invention, it is preferred to mount a resilient stopper 16 snugly over the midportion of the barrel with its smaller end pointing toward the needle end. This stopper is employed to detachably support a test tube 18 having a very small narrow-necked glass tube.19 open at both ends embracing the lower end of needle 14. Container 20 encases tube 19 and is provided with a bulbous enlargement'or bubble breaker 21 surrounding the upper restricted end 22 of tube 19. Tubes 19 and 20 fit loosely within one another and this assembly, in turn, has a loose fit interiorly of the main support tube 18.

The described apparatus is prepared for use by removing the syringe plunger 12 and coupling the discharge end of chromatograph tube 25 to barrel 11 by a gastight section of rubber hose 26. It will be understood that tube 25 is connected by coupling assembly 27 to the particular portion of a chromatograph, not shown, employed to collect the gas to be analyzed.

Prior to passing the effluent into tube 25 and barrel 11, container 20 is charged with a suitable liquid solvent for the effluent to be collected. This operation is performed while holder tube 18 is detached from rubber plug 16. This assembly is then telescoped about the needle end of the syringe until the parts are positioned approximately as shown in FIG. 1. Thereafter the effluent is passed ,into tube 25. In most instances, the transfer of the effluent into the liquid solvent is expedited by the use of a carrier gas and preferably one not absorbed by the solvent for the effluent. It will therefore be understood that the carrier and the admixed efiluent flow downwardly through barrel 11 and needle 14 into the solvent where the eflluent is absorbed and the inert carrier gas bubbles upwardly through the liquid. Any bubbles of solvent which may form during this operation burst upon reaching the expansion chamber provided by the bulbous portion 21 of container 20. As the fluid enters the solvent from the lower end of needle 14 the rising fluids cause the absorbent to circulate upwardly about the needle and downwardly along the exterior of tube 19 thereby promoting the absorption of the efiluent and the escape of the inert gas. In cases where there is no particular tendency of the solvent to form bubbles, tube 19 may be omitted. In cases where very large samples are to be trapped, both container 20 and tube 19 may be removed and container 18 charged with solvent. The inert carrier gas escapes to the atmosphere by way of a suitable vent such as port 29 provided along the lower rim edge of plug 16.

Usually the gaseous sample is quickly absorbed in the liquid solvent but the apparatus is allowed to stand until there is ample assurance that the entire sample has been absorbed. Thereafter hose coupling 26 is disconnected and plunger 12 is immediately inserted in the top of barrel 11. Under certain circumstances it is desirable to elevate the tip of needle 14 above the solvent level while depressing plunger 12 and purging the air from the interior of the syringe. Immediately thereafter the needle is lowered into the bottom of the solvent and the plunger is slowly elevated to draw the solvent 30 into the syringe barrel along with the absorbed effluent sample therein. It is found that forming the bottom of tube 19 with a V-notch 32 and a small hole 33 promotes and facilitates circulation of the solvent during the period of efliuent absorption.

It will be recognized from the foregoing that once the solvent and fluid sample have been transferred into the syringe the sample is, for all practical purposes, sealed from the atmosphere except for the minute surface area exposed to the air at the tip end of the needle. Thereafter the captured fluid sample may be subjected to further analysis in accordance with well-known techniques.

While the particular chromatography apparatus and method herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction of design herein shown other than as defined in the appended claims.

We claim:

1. In chromatographic apparatus for the recovery of a minute quantity of a compound while in a gaseous phase and improvement comprising needle-equipped syringe means having a barrel slidably supporting a removable plunger, means for connecting the open end of the plungerless barrel to a source of the eflluent to be collected in a gastight manner, means for supporting the needle end of the syringe submerged in a small quantity of liquid solvent for the efiluent to be collected whereby the efliuent is absorbed therein, and said eflEtuent connecting means being readily removable and replaceable by said plunger for use in withdrawing the solvent and the etfluent absorbed therein into said syringe.

2. Chromatographic apparatus as defined in claim 1 characterized in that said means for supporting the needle tip submerged embraces the needle end of the syringe and includes an outer tubular container for solvent having its bottom spaced closely adjacent the needle tip thereby to assure delivery of efliuent to the bottom of the solvent therefor. I

3. Chromatographic apparatus as defined in claim 2 characterized in the provision of vent means for venting to the atmosphere a carrier gas for the efliuent to be absorbed in the solvent therefor.

4. Chromatographic apparatus as defined in claim 2 characterized in the provision of means for promoting the circulation of solvent comprising an elongated tubular member telescoped over the needle end of said syringe barrel interiorly of said solvent container and supported therewithin.

5. Chromatographic apparatus as defined in claim 4 characterized in the provision of a third tub-ular contamer embracing said tubular member and located between the latter and the interior surface of said outer tubular container, and said third tubular container having a bulbous enlargement in its side wall eifective to burst bubbles and located adjacent to and surrounding the upper end of said tubular member.

6. Chromatographic apparatus as defined in claim 5 characterized in that said tubular member has a small inlet at its lower end and a restricted outlet at its upper end having slight clearance with the side of the syringe needle, and said outlet being below the upper edge of the bulbous enlargement of said third tubular container.

7. In a chromatographic procedure, that improvement in collecting a minute quantity of a gaseous efliuent for analysis which comprises: conducting said effluent from a source thereof into a liquid solvent for that effiuent through the empty barrel of a syringe while holding the tip of the syringe needle submerged in a small quantity of the liquid solvent until the efliuent is absorbed thereby, inserting a snug-fitting plunger into the upper end of the syringe barrel, and then extending the plunger to withdraw the small quantity of solvent and the efiiuent absorbed therein into the syringe barrel.

8. A chromatographic procedure as defined in claim 7 characterized in the stepsof connecting the top of the empty syringe barrel by fluid-tight means to a source of the efiluent to be collected, holding the liquid solvent for the eflluent in a miniature container embracing the tip end of the syringe needle, and conducting the effiuent into said solvet alog with a carrier gas not absorbable by said solvent, and permitting the carrier gas to escape as the efiluent is being absorbed by the liquid solvent.

References Cited UNITED STATES PATENTS 2,001,581 5/1935 Matuszak 23-292 2,940,448 6/ 1960 Furlong. 3,168,378 2/1965 Maresh et al. 3,171,722 3/1965 Natelson 23-259 XR 3,173,762 3/ 1965 Varadi et al. 23-259 3,205,711 9/1965 Harris 23-259 XR 3,374,660 3/1968 McKinney et al.

FOREIGN PATENTS 509,288 7/1939 Great Britain.

MORRIS O. WOIJK, Primary Examiner B. S. RICHMAN, Assistant Examiner 11.5. C1. X.R. 

